#include <iostream>
#include <vector>

using namespace std;
bool cmp(vector<int> &A,vector<int> &B){
    if(A.size() != B.size()) return A.size()>B.size();
    for(int i = A.size()-1;i>=0;i--)
        if(A[i] != B[i]) return A[i] >B[i];
    return true;
}
vector<int> sub(vector<int> &A, vector<int> &B){
    vector<int> C;
    for(int i = 0,t= 0; i<A.size(); i++){

        t = A[i] - t;
        if(i<B.size()) t -= B[i];
        C.push_back((t+10)%10);
        if(t<0) t = 1;
        else t = 0;
    }
    while(C.size() > 1 && C.back() == 0) C.pop_back();
    return C;
}

int main()
{

    string a, b;
    vector<int> A, B;
    cin >> a >> b;
    for (int i = a.size() - 1; i >= 0; i--)
        A.push_back(a[i] - '0');
    for (int i = b.size() - 1; i >= 0; i--)
        B.push_back(b[i] - '0');
    vector<int> C;
    if (cmp(A, B))
        C = sub(A, B);
    else
        C = sub(B, A), cout << '-';
    for (int i = C.size() - 1; i >= 0; i--)
        cout << C[i];
    cout << endl;
    return 0;
}